Regulation of the heat shock response in Escherichia coli
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University of California
Abstract
All organisms utilize the heat shock response to sense the level of unfolded proteins in
the cell and adjust the level of chaperones and proteases accordingly. The regulation of
the heat shock response has been extensively studied, yet there are still unexplained
components. I report three contributions to our understanding of this regulation. First, I
show that instead of a single chaperone, a chaperone network consisting of at least
DnaK/J and GroEL/S is used to sense unfolded proteins. Second, I provide evidence for
an unexpected link between activity control and regulated degradation of cr32 and suggest
that an additional, unidentified factor contributes to the regulation o f cr32 activity. These
results are based on analysis of a 32 mutants defective in activity regulation. Third, I
demonstrate that Hfq, and potentially small RNA binding partners, contribute to
regulation of a 32 in at least two distinct ways. Hfq represses DnaK translation, which in
turn leads to an increase in a 32 activity. Also, Hfq participates in a process that we have
termed “long-term adaptation”, whereby the activity of o32 recovers to normal levels
following long-term chaperone overexpression.
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Guisbert, E. (2006). Regulation of the heat shock response in Escherichia coli. Retrieved from ProQuest Digital Dissertations. (AAT 3229265)